Natural barium sulfate (also commonly referred to as barite or barytes) is frequently used as an extender pigment and/or filler due to its chemical inertness (in both acid and alkali environments), high refractive index, low abrasiveness, low oil absorption, and resistance to corrosion. Barium sulfate is also known to promote flame retardancy and smoke suppression in polymeric end use applications. Given their high refractive index, barium sulfates of high brightness are desirable to use as a replacement for titanium dioxide (TiO.sub.2) in certain compositions such as pigmented polymeric compounds. Barite can be utilized to replace a portion of the more expensive TiO.sub.2 pigment without having a deleterious impact on the compound's brightness and whiteness properties. Synthetic, precipitated barium sulfate pigments are used in a like fashion, but are typically available in finer particle size grades versus the mechanically ground, natural barites. Precipitated barium sulfate is commonly referred to as blanc fixe.
Despite barium sulfate's many end use advantages, it is not readily wetted or dispersed in organic based formulations such as polymeric compounds given its inert inorganic surface. Accordingly, lengthy processing times are typically required to obtain desired levels of dispersibility of the barite in such compounds. Further, fine and ultrafine particle barites in dry form tend to cake when stored and/or transported. Caking creates processing problems when the barite particles are added to end use formulations via automated dry feeders and the like. Consequently, a general need for barium sulfite with improved processability and dispersibility has existed.
In the vulcanized rubber product fields, fillers have been used to stiffen or reinforce rubber and/or reduce the cost of the rubber formulations, such used as in tires, v-belts, hoses, and so forth. Fillers used in for rubber tire components, for instance, have primarily involved carbon black and/or silicas. Besides, silicas, other non-carbon black fillers for tire rubbers also have been mentioned in the prior art, including calcium silicate, aluminum silicate, clay, talc, calcium carbonate, magnesium carbonate, alumina hydrate, diatomaceous earth, barium sulfate, mica, alumina sulfate and titanium oxide (e.g., see U.S. Pat. No. 5,959,039). Vulcanized rubber applications would be advanced if rubber fillers, which implicitly must be compatible with vulcanizable rubber formulations, could be developed which would enhance the vibration and/or noise dampening properties of the end product without causing a sacrifice of the performance needed in other respects, such as in abrasion/cutting/wear resistance, grip (if applicable), flexibility, rolling resistance (if applicable), and/or manufacturability.